The intent is to allow distros to share common core config but still allow
customisations. The core should work with no distro set but users
can still customise in any ways needed.
(From OE-Core rev: c0a148077ae27a1ef57c55ac22953c68d001af57)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>